1. Field of the Invention
The present invention relates to chamber processing, and more particularly to a method for monitoring the status of system components during a process performed in a batch type processing system.
2. Description of the Related Art
Many semiconductor fabrication processes are performed in process chambers such as for example plasma etch chambers, plasma deposition chambers, thermal processing chambers, chemical vapor deposition chambers, atomic layer deposition chambers, etc. Processing of substrates can lead to formation of material deposits on system components in the process chamber. Periodic dry cleaning of the process chambers can be carried out to remove the chamber deposits, where the cleaning process removes different material deposits from the system components.
Various parts of a processing system can include consumable or replaceable system components that can, for example, be fabricated from quartz, silicon, alumina, carbon, or silicon carbide. The consumable nature of the replaceable components requires frequent maintenance of the processing system. Consumable system parts are commonly replaced or cleaned after film accumulation threatens particle problems, for example between incompatible processes scheduled to be run in sequence, or after detrimental processing conditions, or when poor processing results are observed. Alternately, consumable system parts can be cleaned or replaced according to a predetermined maintenance schedule that can, for example, be based on the number of operating hours. Such maintenance approaches frequently result in overdue or premature replacement of the consumable system components.
Further complications arise because the length of a cleaning process, based on a fixed time period that has been proven to result in adequate cleaning of system components in the past, may differ depending on the history of the system components. Accordingly, the fixed time period may be unnecessarily long, may result in undesired etching (erosion) of the system components, and/or may not adequately restore the system component.
Chamber conditioning processes (also referred to as passivation processes) are commonly implemented in semiconductor fabrication to prepare process chambers for optimal performance. For example, chamber conditioning processes may be carried out following chamber cleaning, after an extended chamber idle period, or before a first chamber production process. When used with plasma chambers, chamber conditioning processes typically involve using a “conditioning plasma” in the plasma chamber for a predetermined length of time to prepare or “condition” the chamber for the upcoming performance of a plasma process involving production wafers. The parameters of the conditioning process (e.g., RF power, chamber and substrate temperature, feed gas composition, an pressure) are usually maintained at or near the parameters of the corresponding production process for which the chamber is being conditioned. In this manner, conditioning processes can help ensure that all processes performed in a process chamber produce results with in a desired range.
Conditioning processes can be performed on several wafers or sets of wafers. The extent of conditioning can be monitored by periodically analyzing the wafers during the conditioning procedure to determine process compliance. However, conditioning processes that are carried out for long time periods involve the use of a large number of test wafers, which result in large startup expenses. Alternatively, the extent of conditioning can be carried out for a fixed time period that has been proven to provide production process compliance. However, because the effectiveness of the conditioning process in not actually monitored, the fixed time period may be unnecessarily long in order to account for varying conditioning times required to achieve process compliance for different runs of a conditioning process. This can result in unacceptable reduction in throughput for the processing chamber.